1. Field of the Invention
The present invention relates generally to electrical connectors suitable for use in control centers including a plurality of control units mounted on a box-shaped frame so that a plurality of electric motors are controlled, and more particularly to the electrical connector having male and female contacts for making and breaking motor main circuits between the control unit side and the box-shaped frame side.
2. Description of the Prior Art
A first embodiment of conventional electrical connector of the above-described type is shown in FIGS. 15 and 16. Reference numeral 1 indicates three vertical buses, for respective phases, for example. Female contacts 2 are provided so as to correspond to the respective vertical buses 1. Each female contact 2 includes an end section 2a and a pair of contact strips 2b extending from respective edges of the end section 2a in an opposite relation with each other. Each connecting conductor 3 is bent to a slender triangular configuration. An end section 3a of the connecting conductor 3 is secured to the end section 2a of the female connector 2 by rivet 4 so that a pair of conductive strips 3b forming generally U-shaped leg portions extend at the outside of the pair of contact strips 2b in a nearly opposite relation therewith. Terminal portions 5 are formed at the distal edges of the conductive strips 3b. Connection wires 6 are connected to the terminal portions 5. The female contact 2 and the connecting conductor 3 integrated therewith are inserted and secured in a cavity 7a formed in a split insulating case 7 so that the outer surface of the conductive strip 3b of the connecting conductor 3 closely abuts on the inside of the cavity 7a. The insulating case 7 is mounted on the backside end of the control unit (not shown).
Where an overcurrent such as short-circuit current flows from the vertical bus 1 into the female contact 2, an electromagnetic force is induced between the contact strips 2b when the short-circuit current flows through the contact strips 2b in the direction of the end section 2a. Since the short-circuit current further flows from the end section 3a of the connecting conductor 3 through the conductive strips 3b in the direction of the terminal portions 5, an electromagnetic repulsive force is induced between the conductive strips 3b and the contact strips 2b. Thus, the electromagnetic attractive and repulsive forces effectively act so that the connection between the contact strips 2b and the vertical bus 1 is held.
However, since the female contact 2 and the connecting conductor 3 integrated therewith are secured in the cavity 7a of the insulating case 7 with the conductive strips 3b closely abutting on the inside of the cavity 7a, the female contact 2 cannot be allowed to move in the cavity 7a. Accordingly, when the female contact 2 is to be connected to the vertical bus 1, the centers of the end openings of three female contacts 3 are required to be exactly aligned with the centers of the corresponding vertical buses 1 simultaneously. Otherwise, it would be difficult to connect the female contacts 2 to the corresponding vertical buses 1.
FIG. 17 illustrates a second embodiment of the conventional electrical connector. A pair of plate-shaped connecting conductors 8 are provided at the outside of the contact strips 2b of the female contact 2 so as to be nearly opposed thereto. The connecting conductors 8 are connected to the end section side of the contact strips 2a by means of rivets 9. The terminal portions 10 similar to the terminal portion 5 are provided at respective edges of the connecting conductor 8. The female contact 2 and the connecting conductor 8 integrated therewith are provided in the cavity 7a of the insulating case 7 so that spaces are formed between the connecting conductor 8 and the inner walls of the cavity 7.
In accordance with the second embodiment of the conventional electrical connector, the connection of the female contacts 2 to the corresponding vertical buses 1 are rendered easier since the spaces at the outside of the connecting conductor 8 allow the female contact 2 and the connecting conductor 8 integrated therewith to move in the cavity 7a. However, when the short-circuit current flows through the female contact 2, for example, the electro-magnetic repulsive force induced between the contact strips 2b of the female contact 2 and the connecting conductor 8 causes the connecting conductor 8 to be displaced outwardly. The electromagnetic repulsive force does not act to bias the contact strips 2b against the vertical bus 1 effectively. Consequently, the electro-magnetic forces induced between the contact strips 2b and the vertical bus 1 owing to the short-circuit current cause the contact strips 2b to be disconnected from the vertical bus 1.